Automobiles and various types of transportation vehicles include a seat belt protecting a passenger from impact. The seat belt is provided with a buckle apparatus for locking/releasing a tongue plate of the seat belt.
The buckle apparatus includes a latch member having a claw pressed to an engagement direction by a spring and fitted with the tongue plate. The tongue plate connected to the seat belt is inserted into the buckle apparatus so that the latch member of the buckle apparatus is fitted with the tongue plate, and the latch member engages with the tongue plate by a locking bar so that the seat belt confines the passenger.
To release engagement of the latch member with the tongue plate, if a release button is pressed in the release direction, the locking bar is moved to a release location so that the tongue plate is released from a buckle.
However, the buckle apparatus has a problem in that the tongue plate moves (hereinafter referred to as ‘up-down movement’) in the direction approximately perpendicular to the insertion direction of the buckle when the tongue plate is inserted into the buckle apparatus.
A buckle for a seat belt according to the related art is disclosed in European Patent No. 0557983 and Korean Utility Model Registration No. 20-0416588.